Caption: Progressive supranuclear palsy. Coloured magnetic resonance imaging (MRI) scan of the brain of a patient with progressive supranuclear palsy (PSP). PSP is caused by lesions over the primary motor cortex. This has caused the cerebral cortex (folded area) to shrink (atrophy). Symptoms include: loss of balance with frequent falls, inability to control eye movements, personality changes and muscle rigidity. There is no cure for the condition.